Apparatuses for crimping and loading of intraluminal medical devices

ABSTRACT

Crimping apparatuses for reducing the diameter of an intraluminal medical device from a first diameter to a second diameter prior to loading the medical device into a catheter delivery system and loading apparatuses for introducing the medical device into a catheter delivery system, the devices constructed and arranged for matingly engaging one another, combinations thereof, and methods of using the devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.12/646,793, filed Dec. 23, 2009, which is a Continuation of U.S.application Ser. No. 11/971,065, filed Jan. 8, 2008, now U.S. Pat. No.7,636,997, which is a Division of U.S. application Ser. No. 10/767,985,filed Jan. 29, 2004, now U.S. Pat. No. 7,316,147, the entire contents ofwhich are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to an apparatus and methods for reducing in sizean intraluminal medical device such as a stent, stent-graft, graft, orvena cava filter, and for introducing the medical device into the distalend of a delivery system for delivery of the medical device into thevasculature of a patient.

Stents and stent delivery assemblies are utilized in a number of medicalprocedures and situations, and as such their structure and function arewell known. A stent is a generally cylindrical prosthesis introduced viaa catheter into a lumen of a body vessel in a configuration having agenerally reduced diameter and then expanded to the diameter of thevessel. In its expanded configuration, the stent supports and reinforcesthe vessel walls while maintaining the vessel in an open, unobstructedcondition.

Stents are available in both self-expanding and inflation expandableconfigurations. Inflation expandable stents are well known and widelyavailable in a variety of designs and configurations. Bothself-expanding and inflation expandable stents are typically crimped totheir reduced configuration after being disposed about a deliverycatheter. They are maneuvered to the deployment site and expanded to thevessel diameter either by fluid inflation of a balloon positionedbetween the stent and the delivery catheter, or upon release of theself-expanding stent from its crimped state, typically from a retainingsleeve or delivery sheath.

A number of techniques for crimping a stent to a balloon are used. Onesuch technique that is commonly used in the radiological suite involveshand crimping the stent to the balloon. A stent is placed over anuninflated balloon and then squeezed with the fingers until the stent isin intimate contact with the uninflated balloon. The technique is highlyoperator dependent and can affect stent profile and stent placement withrespect to the balloon and radiopaque markers. It can also affect thedilatation length of the stent and lead to pinching of the balloon.

Typically, mechanical stent crimping devices are either used to crimpthe stent to the catheter prior to shipping the stent or in theradiological suite. In the latter case, the radiologist selects a barestent with the desired properties and then mechanically crimps the stentto the desired balloon catheter.

Crimping and loading of self-expanding stents is often a morecomplicated procedure. Self-expanding stents are typically loaded into aconstraining structure of a catheter delivery device after crimping ofthe stent. Stent loading typically involves pushing or pulling the stentout of a device in a constricted state and directly into a stentdelivery system, or into an intermediary region and then into thedelivery system. Alignment of the delivery system, typically the distalend of a catheter delivery device, with the crimping device can beproblematic because the stent is relatively fragile, and typically theconstrained outer diameter of the stent is only slightly less than theavailable inner diameter of the receiving delivery system orintermediate station. If the delivery system is not properly alignedwith the crimping device, the stent and/or the catheter delivery systemcan be damaged. The constraining structure for the stent is typically aretaining sleeve or delivery sheath and is often in a tubular form.Damage may involve flaring of the ends of the catheter delivery system,or peeling or rolling of the tubing onto itself.

Thus, there is a continuing need for improved devices and methods forloading a stent onto a delivery system such as a balloon catheter thatare simpler, less expensive, more convenient, more reliable and avoiddamage to the stent.

SUMMARY OF THE INVENTION

The present invention relates generally to an apparatus and method forreducing an intraluminal medical device in size, and for introducing themedical device into the distal end of a catheter delivery assembly.Suitable medical devices include stents, stent-grafts, grafts and venacava filters whether self-expandable or balloon expandable.

In one aspect, the present invention relates to an apparatus forreducing in size an intraluminal medical device, the apparatusconstructed and arranged for matingly engaging an apparatus forintroducing the medical device into the distal end of a catheterdelivery assembly.

Any crimping configuration may be employed herein. Typically, suchapparatuses are designed for applying relatively uniform radially inwardforces to the medical device. The apparatus reduces the size of themedical device from a first diameter to a second diameter. Some suchapparatuses have a plurality of coupled movable blades disposed about areference circle to form an aperture whose size may be varied.

In another aspect, the present invention relates to an apparatus forintroducing an intraluminal medical device into the distal end of acatheter delivery assembly, the apparatus constructed and arranged tomatingly engage an apparatus for reducing a medical device from a firstdiameter to a second diameter.

In one embodiment, the introducing apparatus includes a hollowcylindrical housing, referred to hereinafter as an introducer shaft,which is designed for receiving the medical device. The hollowintroducer shaft is further equipped with a hollow plug which tapersfrom one end having a larger opening to the other end having a smalleropening. The plug is insertable into the hollow cylindrical housing. Theplug tapers from one end which has a larger opening, the larger openingbeing located at the end of the housing into which the medical device isfed, to a smaller end, the smaller end engaging the distal end of acatheter delivery assembly.

The plug may be of a variety of configurations. In one embodiment, theplug has conical flanges extending from the end closest the catheterdelivery assembly. The conical flanges may be designed such that theymore easily engage the outer catheter shaft.

In another embodiment, the plug has straight edges.

In one embodiment, the introducer shaft has an external triangular formwhich fits into a lumen of the introducer apparatus. This allows for airto flow around the sides of the housing through the lumen.

The present invention also relates to combinations of theabove-described apparatuses.

In one embodiment, the apparatus for reducing the medical device in sizeincludes at least three coupled, movable blades disposed about areference circle to form an aperture whose size may be varied. Theapparatus further includes at least one alignment tool connected to atleast one blade. The at least one alignment tool may be integral with ormodular with the at least one blade.

In another embodiment, each blade has an alignment tool such that aclosed alignment shape is formed with the motion of the blades. Thealignment tools may either be an integral part of each of the blades, ormay be modular with the blades. The latter case allows for differentalignment shapes to be incorporated depending on particular applicationfor which the aperture is being used.

As used herein, the term “integral” when used in reference to analignment tool being integral with a blade shall refer to thosealignment tools which are formed as part of the blades themselves, orare secured such that they are not readily removable from the blades.

As used herein, the term “modular” when used in reference to analignment tool being integral with a blade shall refer to thosealignment tools which are readily removable from the blades.

Furthermore, the alignment tools may be designed such that they form acontinuous alignment shape around the aperture, or they can be designedto allow for spacing between the blades which form the aperture. Thelatter case may be employed for use with a sheath or sleeve mechanism,for example, or to gain access to the tip of the crimped medical devicewith the delivery system already in place.

The alignment tool according to the present invention may of course beemployed with any apparatus which is employed to uniformly reduce thesize of a medical device. These devices are often referred to ascrimpers or crimping devices. Such devices are described, for example,in commonly assigned U.S. Pat. No. 6,360,577, in US Provisional PatentApplication Publication No. US 2002/0138966 A1 and in US Patent7,021,114, for example, each of which is incorporated by referenceherein in its entirety.

The present invention also relates to methods of using the apparatusesdescribed herein. In one embodiment, the present invention relates to amethod of crimping and loading a medical device into a catheter deliverydevice, the method including the steps of providing a crimping apparatushaving an actuation hub for matingly engaging a loading apparatus,placing the medical device into the crimping apparatus, applying aradial inward force while the medical device is in the crimpingapparatus such that the diameter of said medical device is reduced froma first diameter to a second diameter, providing a loading apparatushaving a plug for matingly engaging said crimping apparatus, mating thecrimping apparatus and the loading apparatus and transporting themedical device from the crimping apparatus to the loading apparatus, thesteps not necessarily in that order.

The present invention, in at least some of its embodiments, thereforeprovides for improved alignment of the medical device with the apertureof the crimping tool thereby alleviating the need for calibration or forexternal alignment efforts to the aperture axis. Furthermore, at leastsome of the apparatuses as described herein, reduce the risk of damageto the intraluminal medical device and/or the catheter delivery assemblyduring transition from the crimping apparatus to the introducerapparatus.

Other benefits and advantages and will become apparent from thefollowing description.

All patents discussed herein are incorporated by reference herein intheir entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an actuation hub for use with any crimping apparatusaccording to the present invention.

FIG. 2 illustrates an introducer plug for a stent loading assemblyaccording to the present invention.

FIG. 3 is a schematic side view of a self-aligning loading assemblyaccording to the present invention.

FIG. 4 is a simplistic flow diagram showing movement of a stent into aloading chamber through a transition tube and into the aperture of acrimping apparatus.

FIG. 5 shows an aperture of a type of crimping apparatus which may beused in combination with the present invention.

FIG. 6 illustrates blades for a crimping device having modular alignmentstructures on the blades.

FIG. 7 illustrates blades for a crimping device having integralalignment structures on the blades.

FIG. 8 illustrates blades for a crimping device having alternativemodular alignment structures on the blades.

FIG. 9 illustrates blades for a crimping device having alternativeintegral alignment structures on the blades.

FIG. 10 is a partial view of a crimping apparatus having blades withintegral alignment structures according to the invention shown incombination with a catheter shaft.

DETAILED DESCRIPTIONS OF THE INVENTION

While this invention may be embodied in many different forms, there aredescribed in detail herein specific embodiments of the invention. Thisdescription is an exemplification of the principles of the invention andis not intended to limit the invention to the particular embodimentsillustrated.

Turning now to the figures, FIG. 1 illustrates generally at 5, aninternally tapered actuation hub which may be used in combination withany crimping device. As used herein, the term “crimping” shall refer toa reduction in size or profile of the medical device, i.e. the diameterof a stent, for example. The actuation hub 5 is employed for matinglyengaging a loading assembly for introducing an intraluminal medicaldevice into a catheter delivery assembly. The intraluminal device istypically introduced when its in a reduced size.

The tapered actuation hub 6 may be employed to matingly engage acounterpart plug on a stent loading assembly such as that showngenerally at 10 in FIG. 2. Plug 10 is shown with an externally taperedhead 12. Shown in FIG. 2 is also an introducer shaft 26 which isdisclosed in more detail in FIG. 3 below. The stent introducer shaft 26is further equipped with a stent introducer plug 28 which is alsodisclosed in more detail in FIG. 3 below.

The actuation hub 5 may be employed in combination with any type ofcrimping device. Examples of such devices are found in U.S. Pat. No.6,360,577, US Patent Application Publication No. 2002/0138966 A1, U.S.Pat. No. 6,568,235 B1, each of which is incorporated by reference hereinin its entirety.

FIG. 3 schematically illustrates generally at 20, an embodiment of anintraluminal medical device loading assembly or introducer assembly inaccordance with the present application in which an actuation hub 5 of acrimping device which may be any crimping device, is shown matinglyengaged with the loading assembly 20 using a plug 10 as shown in FIG. 2.Stent 25 is shown partially within the aperture 48 of a crimping device14 and between crimping blades 22.

A pushing quill 24 is behind stent 25 and moving stent into introducershaft 26 of stent loading assembly 20. Within introducer shaft 26 iswhat may be referred to as a stent introducer plug 28. Pushing quill 24may be actuated pneumatically or mechanically. Stent introducer plug 28is shown with a tapering lumen. As can be seen from FIG. 3, the diameterof the opening of the introducer plug 28 is slightly larger than thediameter of the aperture 48 of the crimping apparatus 14. The diameterof the opening of the introducer plug 28 adjacent the catheter shaft 35is slightly larger than the diameter of the opening of the cathetershaft 35. Catheter shaft 35 is shown having a flared end 34. The flaredtip may be trimmed off after the stent has been loaded and thecrimping/loading procedure is complete. Stent introducer plug 28 isshown in this embodiment with flanged ends 36 which are constructed andarranged in this embodiment to easily engage the flared end of the outercatheter shaft 35. However, stent introducer plug 28 as well as thedistal end 34 of catheter shaft 35 may also be provided without theflare and may, for example, be configured with a flat edge as well.

Having a tapered introducer plug 28 as such, allows for the diameter ofthe intraluminal medical device 32 to be decreased more prior to loadinginto the shaft of the catheter delivery assembly. Furthermore, theinternal taper of the bore extending through introducer plug 28 may bedesigned such that the bore is slightly larger in diameter than theaperture 48 of a crimping apparatus 14 at the end of the bore closest tothe crimping apparatus, which is explained in more detail below, and isslightly smaller in diameter than the diameter of the distal end of theouter catheter shaft of the catheter delivery assembly.

Stent introducer plug 28, having a lumen 30 with an internally taperedsurface, may be removable from stent introducer shaft 26 andinterchangeable such that the size and configuration may be varieddepending on the medical device which is to be introduced into the outercatheter shaft. Furthermore, the stent introducer shaft 26 may also beremovable from the stent loading assembly 20.

The length of the introducer plug 28 can be advantageously controlled tobe about the same as or just slightly less than the length of a stentstrut. During at least a portion of stent loading, one strut is in theintroducer plug 28, one strut is in the chamber 48 and one strut is inthe catheter 35. Having most all of the entire distance from one strutto the next in the introducer plug 28 facilitates reduction such that itis easier to introduce the next strut into the catheter shaft. Havingthe length of the tapered introducer plug 28 to be slightly less than astent strut also allows forced transference of the stent from theaperture 48 of a crimping apparatus 14, into the introducer plug 28,without snagging a strut, and allows for the stent to have a slightlyreduced outside diameter at the strut ends during entrance into theouter catheter shaft 35. The length of the introducer plug 28 issuitably about 0.001 inch to 1 inch (about 0.025 mm to about 25.4 mm),and more suitably about 0.025 inches to about 0.075 inches (about 0.635mm to about 1.905 mm). In one embodiment, the length of the introducerplug is 0.050 inches (about 1.270 mm).

Many stents are formed having a node/strut structure. Having a stentintroducer plug with a length less than one strut or less than thedistance between nodes, as described above, can be advantageous in thatthe change in diameter is affected more in the nodes of a stentstructure, than in the struts. For stents formed from shape memoryalloys such as the nickel-titanium, i.e. nitinol, alloys, this may allowfor the martensitic state to be introduced into each node specifically,resulting in a lower deployment force. In the martensitic state, theradial and frictional forces of the nitinol type of stents are reducedwhile in the austenitic state the radial and frictional forces arehigher. When nitinol stents are stressed, they go into the martensiticstate. They may be stressed either by cooling, or by stress, or both.

Thus, the present method may allow stressing of the stents and thusentry into the martensitic state without cooling. Having the stents in amartensitic state thus allows for lower frictional, i.e. the radialforce, and deployment forces, i.e. those required to push the stent outof the catheter shaft. This type of phenomenon is discussed in U.S. Pat.No. 6,306,141 which is incorporated by reference herein in its entirety.

The shaft 26 may be attached to a horizontally mounted hollow rodpneumatic cylinder 42. If employed in combination with a crimping systemas described above, when the aperture 48 of the crimping apparatus 14 isopen, the shaft 26 moves into the aperture 48 of the crimping apparatus14. A stop (not shown) may be placed in the aperture that halts thetravel of the intraluminal medical device or stent 25 within theaperture 48 and stops the stent from proceeding too far through theaperture. Once the stent is in the aperture 48 of the crimping apparatus14, the stop is desirably removed. During crimping, the intraluminalmedical device typically elongates along its axis as the diameter isreduced. If the stent is not allowed to elongate, the reduction in thediameter will not be uniform. Thus, the stop is removed. This may alsoprevent catching of the stent between the introducer plug 28 and theblades 22.

A forced air system designed to either heat or to chill the stent, forexample, cryogenically, can also be used to transfer the stent throughthe system. The stent may be moved into the aperture 48 of the crimping,loading apparatus indicated generally at 14, 20 using a forced airsystem where it is transferred through a tube or some such structure.Forced air, rather than using a pushing device, will reduce thepotential of damaging the stent by pushing it into the aperture 48 withan object. Using a triangular shaped introducer shaft as shown in FIG.2, offers benefits when using such forced air. The triangular shapedintroducer shaft 26 is shown within a circular lumen 27 of theintroducer assembly 10 in FIG. 2. This configuration allows for air flowaround the entire introducer shaft, thus providing better, more uniformheating and cooling of the entire shaft, and consequently better heatingand cooling of the stent within the shaft.

Using a recirculating air system can prevent internal frost build-up inthe system. A forced air system may be employed to transfer the stentthrough the system as well as for heating and cryogenically chilling thestent.

The stent may be placed in a loading chamber assembly 50 shown in FIG. 4and released from the loading chamber using a stent pin. The stent isthen moved from the loading chamber assembly 50, through the transitiontube 52 and into the aperture 48 of the crimping/loading apparatus 14and from there into a catheter tube 35. Forced air may be employed tomove the stent from the loading chamber 50, through the transition tube52 and into the aperture 48.

Once crimped, the stent is then moved through the plug lumen into theintroducer shaft. As noted above, with a forced air system, anintroducer shaft having a triangular external shape allows air to flowaround the entire introducer shaft, allowing for better more uniformheating and cooling of the introducer shaft and thus better more uniformheating and cooling of the stents within the introducer shaft.

Optionally, cooling may take place in the loading chamber assembly 50 aswell.

Desirably, the transition tube 52 through which the stent is moved fromthe loading chamber to the aperture 48 of the crimping apparatus is “s”shaped. This allows the pushing quill 24 to be aligned with the apertureof the crimping device such that the pushing quill 24 and the transitiontube 52 do not interfere with one another. Pushing quill 24 may beactuated pneumatically or mechanically and is shown connected to anactuation device 54. The pushing quill 24 is employed to move the stentfrom the aperture of the crimping device and into the catheter shaft 35once the diameter size of the stent has been reduced and crimping isthus complete. The pushing quill 24 is then retracted and another stentmoved into the aperture 48 of the crimping apparatus 14. The next stentmay then be placed in the loading chamber 50.

An operator may then slide the distal end of the outer catheter shaftfrom the product tray 46 into the introducer shaft 26 until it engagesor comes into contact with the introducer plug 28 as shown in FIG. 3. Aproduct hold cylinder and slip clamp 44 puts pressure onto the outercatheter shaft 35 as the horizontal air cylinder 40 retracts from theaperture 48 of the crimping apparatus. A die having a surface with a lowcoefficient of friction, such as by using a polytetraflouroethylene(PTFE), i.e. Teflon® die or Teflon® coating, can be beneficial.Furthermore, the die may be slightly smaller than the outer cathetershaft 35. This may further facilitate placing of the catheter shaft 35over the ends 36 of the introducer plug 28. This action creates forcedpressure onto the outer catheter shaft 35 allowing the introducer plug28 to flare the ends of the outer catheter shaft 35. This flaring canhelp to prevent the nodes of the stent from catching on the outercatheter shaft 35 which can result in delamination of tube layers if theouter catheter shaft has a multilayer construction, for example.

Upon completion of the stent load, the quill 24 retracts, the apertureof the crimping device opens, and the introducer shaft extends into theaperture prepared for the next load.

The present inventive concepts may be employed in combination with anycrimping apparatus. Such crimping apparatuses are known to those ofskill in the art. For example, U.S. Pat. No. 6,360,577 B2, U.S. Pat. No.6,568,235 B1 and U.S. Patent Application Publication No. US 2002/0138966A1, are all examples of such crimping apparatuses, each document ofwhich is incorporated by reference herein in its entirety. The presentinvention is not limited by the type of crimping apparatus which isemployed.

FIG. 5 is an example of one configuration of a crimpingaperture/apparatus which may be used in accordance with the presentinvention. This crimping apparatus includes eight coupled movable blades106 disposed about a reference circle 114 to form an aperture 118 whosesize may be varied. Crimping apparatuses of this type are described inU.S. Pat. No. 6,360,577.

The apparatus may have as few as three blades, and as many as sixteen ormore blades, limited only by how many blades may physically be coupledtogether, under the relevant size constraints. As the number of bladesis increased, the profile of the aperture and hence of the medicaldevice following reduction in size, becomes smoother.

Thus, a medical device may be manipulated using a device as describedabove by application of a radial inward force. The medical device isplaced into the shrinkable aperture formed by the blades disposed abouta reference circle and the blades are simultaneously moved inward toapply a radial inward force to the medical device.

The blades of such crimping apparatuses as those described above may bevaried in order to provide improved alignment of the crimping apparatuswith an introducing apparatus for loading an intraluminal medical devicefrom the crimping apparatus and into an outer shaft of a catheterdelivery assembly, for example. FIG. 6 illustrates blades having modularalignment structures 108 attached to the ends of the blades. Thesealignment structures are shown as conical flanges extending from the endof the blades. The alignment structures 108 may be formed from the samematerial as the blades 106, or from a different material than the blades106. The alignment structures 108 may be attached using any means knownin the art including usual fastening devices, as well as adhesively, forexample. The modular nature of these structures allows for quickinterchangeability if different sizes or structures are desired. Anynumber of the blades may be provided with such structures to improvealignment and facilitate loading of the intraluminal medical device intoan outer shaft of a catheter delivery assembly without damage to themedical device or to the outer shaft.

FIG. 7 illustrates blades of a similar structure to those shown in FIG.6. However, these conical flanges are integral with the blades. In suchan embodiment, the blades are formed from the same material as theblades.

FIG. 8 illustrates blades 106 having alignment structures of a differentconfiguration than those shown in FIG. 6. While these alignmentstructures 108 are also modular with the blades 106, as are the onesshown in FIG. 6, they are connected along the length of the blade 106rather than at the edge.

FIG. 9 illustrates alignment structures 108 similar in configuration tothose shown in FIG. 8, but which are integral with the blades 106.

FIG. 10 is a partial view of a crimping apparatus according to theinvention wherein blades 106 have integral alignment structures 108shown in combination with a catheter shaft 35 with a flared end 34. Oncecrimping and loading is complete, the flare is cut from the cathetershaft.

The crimping apparatus and method of the present invention is adaptablewith thermal capability to operate at temperatures ranging between 37°C. and 300° C. by placing heater cartridges in the segments through itsback. The apparatus and methods are adaptable with cryogenic capabilityto operate at temperature ranging between −200° C. and −37° C. Liquidnitrogen may be used to cool the segments or to cool the housing plates.Thus, the apparatus and method are useful for those medical devices madefrom materials such as the shape memory nickel-titanium alloys. Thesealloys are often referred to in the industry as nitinol.

Such alloys undergo a transition between an austenitic state and amartensitic state at certain temperatures. When such alloys are deformedwhile in the martensitic state, the deformation is retained until theyare heated to a transition temperature, at which time they begin torevert to their original configuration as they start to transform totheir austenitic state. As the temperature increases, the transitioncontinues until the material is entirely in its austenitic phase and hasreverted to its original configuration. The temperatures at which thesetransitions occur are affected by the nature of the alloy and thecondition of the material. Nickel-titanium-based alloys (NiTi), forexample, have a transition temperature which is slightly lower than bodytemperature. Thus, expandable, intraluminal medical devices formed fromnickel-titanium alloys like nitinol, will revert to their austeniticstate when implanted in a body.

Self-expanding stents formed from nitinol are deformed in themartensitic state for loading onto a constraining delivery system. Thecolder temperatures causes the crimped nitinol stent to stay at thereduced diameter. Additionally, it is believed that the coldertemperatures make nitinol more malleable which reduces fatigue. Theapparatuses described above can be advantageously employed for crimpingand loading of intraluminal medical devices formed from such alloys.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. All these alternatives and variations areintended to be included within the scope of the attached claims. Thosefamiliar with the art may recognize other equivalents to the specificembodiments described herein which equivalents are also intended to beencompassed by the claims attached hereto.

The invention claimed is:
 1. A system comprising: a crimping apparatusfor reducing the diameter of the medical device from a first diameter toa second diameter, the crimping apparatus having at least three coupled,movable blades that form an aperture whose size may be varied; a loadingapparatus for loading the medical device into the catheter deliveryassembly, the loading apparatus matingly engaged with the crimpingapparatus; a fluid system in fluid communication with at least thecrimping apparatus, wherein the fluid system conveys a pressurized,cryogenic fluid to transfer the medical device into the aperture of thecrimping apparatus.
 2. The system of claim 1, wherein the loadingapparatus has a shaft and a plug within a lumen of the shaft, whereinthe plug has a lumen and the fluid system further conveys thepressurized fluid to at least the lumen of the plug to transfer themedical device into the loading apparatus.
 3. The system of claim 2,wherein the shaft of the loading device has a triangular shape.
 4. Thesystem of claim 1, wherein the fluid is air.
 5. A loading apparatus forloading a stent into a catheter delivery system, said loading apparatusmatingly engaged with a crimping apparatus for reducing the diameter ofthe stent from a first diameter to a second diameter, said crimpingapparatus comprising at least three coupled, movable blades which forman aperture whose size may be varied, said loading apparatus having ashaft with a lumen and a plug engaged with the lumen of the shaft, theplug having a length that is slightly less than the length of a strut ofthe stent.
 6. The loading apparatus of claim 5, wherein the shaft has anexternal triangular configuration.
 7. The loading apparatus of claim 5,wherein the plug has flanged edges extending from an end of the plug. 8.The loading apparatus of claim 5, wherein the plug has flat edgesextending from an end of the plug.